A bartender at the Stage Deli says transit workers who thought they were about to go on strike last week inadvertently smashed his kneecap by tossing a tire down a subway staircase.

Frank Aliaga had just ended his shift at the Seventh Avenue eatery at 1 a.m. on Dec. 15, and planned to catch the E train home to Elmhurst, Queens.

But at the 53rd Street station, he saw some transit workers apparently preparing for the strike, which was supposed to begin last Friday but was put off for the weekend. Hearing that the train wasn’t running, he headed upstairs.

What he found was “a bunch of people by the stairs chanting, ‘We’re going to strike! We’re going to strike!’ ”

Suddenly, a huge tire fit for a truck came bounding down the staircase.

“The tire hit me right on my leg and knocked me down the stairs,” said Aliaga, 36, who was taken to Roosevelt Hospital, which did not release him until a week later.

Lawyer Roy Silverberg said he would file a $25 million suit next week against the Metropolitan Transportation Authority and the Transport Workers Union.